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Collembola (springtails) < 6 mm ca. 6,000 species worldwide > 300 million individuals/acre have been found in grasslands inhabit soils, leaf litter, fungi, decaying organic matter feed on decaying vegetations and fungi; a few species are herbivores and predators common in grassy and wooded habitats

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Bristletails and Jumping Bristletails 7 – 15 mm ca. 300 species worldwide inhabit leaf litter and decaying organic matter some species are common in buildings and feed on starches in books, wallpaper, clothing, and paper (silverfish) feed on decaying organic matter, fungi, algae, some plant material live in grassy and wooded habitats jumping bristletails are very common in shrubsteppe

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Centipedes ca. 2,500 species worldwide 1 pair of legs per body segment (15 – 177 pairs, depending on species) first pair of legs modified into venemous fangs found in or on soil surface in moist habitats, under bark, stones, and logs predators (on insects, spiders, other small animals)

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Millipedes ca. 2.5 – 10.0 cm ca. 80,000 species worldwide 2 pairs of legs on most segments (30 – 375 pairs of legs, depending on species) found in or on soil surface in moist habitats, under bark, stones, and logs most species feed on decaying organic matter; a few species are predators and herbivores

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Earwigs ca. 1.5 – 2.5 cm ca. 1,800 species worldwide most have a pincer used for grooming, defense, and courtship found in or on soil surface in moist habitats, under bark, stones, and logs most species are scavengers or herbivores, feeding on a variety of plant and animal matter; a few species are predators

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Beetle larvae Predaceous Forms larvae of ground beetles live in burrows in the soil, under leaf litter, logs occur in grassy fields, crop fields generalist predators on other invertebrates; some species feed on snails and slugs Mealworms larvae of darkling beetles occur in grasses, stored grains, forests feed on live and dead plant material

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Moth larvae (cutworms, armyworms, webworms) larvae have well-developed head capsules with chewing mouthparts larvae have 3 pairs of legs on the thorax and 2-5 pairs of prolegs common in grasses and cropland herbivores on plant roots and shoots can occur in very high numbers (e.g., sod webworms in grasslands) can be significant crop pests

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Ant ca. 9,500 described species widely distributed in a variety of habitats build nests in the ground or wood occur in very high numbers in colonies (e.g., 5,300 ants/m 2 in a tropical lowland forest in Brasil) have castes (e.g., workers, queen, soldiers) some species are seed-feeders (e.g., harvester ants) some species are strict predators (e.g., army ants, fire ants) some species omnivore, feeding on plants and animals most species are opportunistic foragers – feeding on a variety of live and dead plant material “ecological engineers” – alter soils and environments

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Pseudoscorpions ca. 2 – 8 mm ca. 200 species in North America large pincer-like claws; no stinger most species have a venom gland found in leaf litter and under bark and stones predators on small invertebrates (e.g., moth larvae, beetle larvae, ants, mites) some live under the wings of beetles and feed on mites

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Mites usually < 1 mm (up to 10 mm) ca. 45,000 described species extremely abundant in some habitats (e.g., up to 1 million per m 2 of coniferous forest litter) found in most terrestrial and aquatic habitats abundant in leaf litter and decaying organic matter feed on plants, organic matter, fungi, bacteria, protozoa, and animals influence decomposition by shredding and feeding on organic matter, and fungi. some are major crop pests

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Spiders ca. 2,500 species in North America found in all terrestrial habitats most have 8 eyes have poison glands some species spin webs eggs often laid in silken sacs predators on many invertebrates

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Harvestmen (daddy longlegs) ca. 5,000 described species worldwide have at most 2 eyes have no poison glands or fangs do not produce silk prefer moist habitats; found in forests, caves, grasslands feed on other invertebrates, plant material, decaying organic matter, fungi

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Earthworms over 7,000 species worldwide no eyes occur in most temperate soils and many tropical soils can have 50 – 300 earthworms/m 2 of crop soil prefer soils with abundant organic matter feed on organic matter and plant materials in soil; obtain nutrients from bacteria and fungi in organic matter take soil in and deposit undigested food as “worm castes” can produce tons of casts per acre each year facilitate nutrient cycling, nutrient mineralization, and decomposition can turnover the top 15 cm of soil in 10 – 20 years

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Nematodes typically < 1 mm about 20,000 described species can be very abundant (millions/m 2 ) many trophic forms fungal feeders bacteria feeders predators on other nematodes and protozoa omnivores (feed on a variety of organisms) herbivores on plant roots animal parasites recycle nutrients by feeding on soil microbes and decomposing organic matter